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TBC 2C caused backup lights stay on

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6.1K views 7 replies 4 participants last post by  Silverado05  
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#1 ·
About a month ago, my backup lights stay on randomly. Sometimes it stay on for days, sometimes it stay on for few minutes. I had to remove bulbs temporary to prevent draining the batteries. It happened around same time when the headliner took out for re-upholstery. I checked the fuse box under the hood, I pulled almost every fuse except TBC BAT that pointed to BCM. I was able to narrow down the specific fuse. It is driver side fuse box - TBC 2C 15A that turn off backup lights. Without TBC 2C fuse, I put gear in reverse - the backup lights turn on no issue so I know it is not backup light fuse under the hood. Can anyone chime in what TBC 2C actually do? TBC 2A and TBC 2B - The dome lights, cluster lights are working fine. Keyless system are working fine so I need to know where the actual wrings goes for TBC 2C. The fuse did NOT blow so I suspected something that trigger backup lights stay on. Does TBC-2C run same driver A pillar along with TBC-2A or 2B?

TBC 2C Fuse 15A Body Control Module (BCM)
 
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#5 ·
I assume your Suburban is a gas model?
Those 2 fuses feed the truck body computer. Looks like a general power feed. their power comes from LBEC1 fuse and it gets power from the main power bus.

What exact problem are you having? Very hard to figure out 'similar' and lighting is almost always not easy.
 
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#6 ·
Yes it is a gas model 1500 with the 5.3 the problem that I’m having is battery drainage. When I come out to start the truck in the morning sometimes it starts then others it won’t. It isn’t only over night from the beginning of work until lunch break 6hours and it doesn’t want to start. I did a parasitic draw test and the only fuse with a significant draw was the TBC 2C. Thanks for the reply!
 
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#7 ·
You need to find wiring diagrams for your 2005 gas Suburban with 5.3L engine and see what that fuse feeds, and then see what is downstream and start looking there. I don't have any access to such a diagram, sorry. If at all possible, fully charge your battery overnight, and any time your battery seems to be down even a little. Battery health is very important. There are many places that will test your battery for free, Walmart being one of them and they are almost everywhere and they have excellent battery test equipment. And the ground for the battery is extremely important, remove the ground side of the battery cable and clean it and the attachment point until shiny before replacing it.

While you are troubleshooting, make sure everything in your truck is turned off at the end of the day (or at work) to eliminate those possibilities, remove everything from the DLC diagnostic port, any aftermarket electronics, scan tool, engine monitor, extra fuel pump, etc. Everything that didn't come from the factory. You are trying to eliminate the most likely problems before starting your search.

Best of luck
 
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